At 09:06 AM 5/10/2007 -0400, Benji York wrote: >I would let Jim speak for himself too, but I prefer to put words in his >mouth. ;) While zope.interface has anemic facilities for "verifying" >interfaces, few people use them, and even then rarely outside of very >simple "does this object look right" when testing. It may have been >believed verification would be a great thing, but it's all but >deprecated at this point.
Okay, but that's quite the opposite of what I understand Jeff to be saying in this thread, which is that not only is LBYL good, but that he does it all the time. >>And thus, for all of the use cases you just described, the minimal >>PEP 3124 Interface implementation should do just fine, yes? > >Could be, especially if it allows for adaptation. Yes, it does. In fact, adaptation is pretty much all they're good for, except for specifying argument types: http://python.org/dev/peps/pep-3124/#interfaces-and-adaptation http://python.org/dev/peps/pep-3124/#interfaces-as-type-specifiers >My main intent in piping up was >dispelling the LBYL dispersions about zope.interface. ;) Well, "back in the day", before PyProtocols was written, I discovered PEP 246 adaptation and began trying to convince Jim Fulton that adaptation beat the pants off of using if-then's to do "implements" testing. His argument then, IIRC, was that interface verification was more important. I then went off and wrote PyProtocols in large part (specifically the large documentation part!) to show him what could be done using adaptation as a core concept. >If the PEP cooperates as well with zope.interface as you suggest, all >will be good in the world. Personally I'd prefer sufficient hooks be >added to the language and these types of things (interfaces, adaptation, >generic functions, etc.) be left to third parties (like yourself) >instead of being canonicalized unnecessarily. Well, as Nick Coghlan's already pointed out, the PEP is mostly about creating a standard set of hooks, so that each framework doesn't have to reinvent decorators and syntax. >>Indeed, ABCs would work for those use cases too, if you didn't need >>adaptation. Or am I missing something? > >The main advantage I see to zope.interface is adaptation. Other >than that, the fact that the inheritance and interface hierarchies >aren't mixed. In which case, you might well be happy with PEP 3124 interfaces, unless you want to use instance-specific interfaces a lot. >I would turn the argument around and assert that interfaces can be used >for the rare LBYL uses that ABCs appear to be aimed at, as well as more >interesting things. Sure, which is another reason why PEP 3124 includes them. _______________________________________________ Python-3000 mailing list Python-3000@python.org http://mail.python.org/mailman/listinfo/python-3000 Unsubscribe: http://mail.python.org/mailman/options/python-3000/archive%40mail-archive.com
